Golf club shaft

Abstract

A hollow, fiber-reinforced plastic golf club shaft is disclosed which is tapered from the grip to the hosel and which is provided with an enlarged portion in an intermediate portion so that the flexural rigidity of the shaft is abruptly changed at the enlarged portion.

What is claimed is: 
     
       1. A hollow golf club shaft having a tip end and a grip end and formed of a fiber-reinforced plastic, said golf club shaft comprising in adjacent order from said tip end to said grip end a hosel section, a first intermediate section, a protruded section, a second intermediate section, and a grip section; said first intermediate section having varying outer diameter increasing from its junction J1 with said hosel section to its junction J2 with said protruded section;   said second intermediate section having varying outer diameter increasing from its junction J3 with said protruded section to its junction J4 with said grip section;   said protruded section having varying outer diameter increasing from said junction J2 to an apex point between said junction J2 and said junction J3 and decreasing from said apex point to said junction J3;   the outer diameter of said shaft at said junction J3 being greater than that at said junction J2;   said junction J3 being located at a position spaced apart from said tip end a distance equal to 35-80% of the length from said tip end to said grip end; and   the distance between said junction J2 and said junction J3 being in the range of 50-400 mm.   
     
     
       2. A golf club shaft as claimed in claim 1, wherein the outer diameter of said shaft at said apex point is greater by 0.3-3 mm than that at said junction J3. 
     
     
       3. A golf club shaft as claimed in claim 1, wherein the taper of said protruded section between said junction J2 and said apex point is in the range of 0.1-6.5% and the taper of said protruded section between said apex point and said junction J3 is in the range of 0.1-6.5%. 
     
     
       4. A golf club shaft as claimed in claim 1, wherein the distance between said junction J2 and said apex point is greater than that between said apex point and said junction J3. 
     
     
       5. A golf club shaft as claimed in claim 1, wherein the inside diameter of said shaft increases from a first point K1 located between said tip end and said junction J1 to a second point K2 located between said junction J1 and said junction J2 and from said second point K2 to a third point K3 located between said junction J4 and said grip end. 
     
     
       6. A golf club shaft as claimed in claim 5, wherein the taper of the outside surface of said shaft is as follows:   ______________________________________                                    
between said junctions J1 and J2:                                         
                       0.1-1.5%                                           
between said junction J2 and apex point:                                  
                       0.1-6.5%                                           
between said apex point and junction J3:                                  
                       0.1-6.5%                                           
between said junctions J3 and J4:                                         
                       0.1-1.5%                                           
______________________________________                                    
     while the taper of the inside surface of said shaft is as follows:     ______________________________________                                    
between said tip end and first point K1:                                  
                         0-4%                                             
between said points K1 and K2:                                            
                       0.2-4%                                             
between said points K2 and K3:                                            
                       0.4-2%                                             
between said point K3 and grip end:                                       
                          0-2%.                                           
______________________________________                                    
     
     
     
       7. A golf club shaft as claimed in claim 5, wherein the taper of the outside surface of said shaft is as follows:   ______________________________________                                    
between said junctions J1 and J2:                                         
                        0.3-1%                                            
between said junction J2 and apex point:                                  
                        0.5-4%                                            
between said apex point and junction J3:                                  
                          1-5%                                            
between said junctions J3 and J4:                                         
                        0.4-1%                                            
______________________________________                                    
     while the taper of the inside surface of said shaft is as follows:     ______________________________________                                    
between said tip end and first point K1:                                  
                       0-3%                                               
between said points K1 and K2:                                            
                       0.4-2%                                             
between said points K2 and K3:                                            
                       0.5-1.5%                                           
between said point K3 and grip end:                                       
                          0-1.5%.                                         
______________________________________                                    
     
     
     
       8. A golf club shaft as claimed in claim 1, wherein said junction J3 is located at a position spaced apart from said tip end a distance equal to 40-75% of the length from said tip end to said grip end, the length of said shaft is 850-1,200 mm, and wherein the distance between said junction J2 and said junction J3 is in the range of 80-350 mm.